Andrew Coyne again is stumping for changes in British Columbia's electoral law. BC dodged the bullet in 2005 but is giving the revolver another spin on Tuesday.
The best argument for Canada's shifting to Proportional Representation would be that it might weaken some otherwise pretty persistent regional voting patterns that reward regional bloc parties. BC's adopting the system could help push it to be put in place nationally. But that doesn't outweigh the costs.
Foremost among the costs of PR is that it consistently delivers minority governments. Canada's had a few of these lately, mostly because Duverger's Law doesn't hold well when there are strong regional cleavages: it predicts two-party races at the district level, but when there's strong heterogeneity across the country, you can get Bloc Quebecois/Liberal fights in Quebec, Conservative/Liberal fights in the Prairies, Conservative/NDP fights in BC, Liberal/Conservative fights in some parts of Ontario and NDP/Liberal fights in others leading to a multi-party parliament. This is by no means set in stone: Canada usually produces single party governments. But a move to PR would entrench coalition governments. Torsten Persson and Guido Tabellini have shown that PR tends to lead to increases in government spending because of the payoffs to small parties necessary for forming coalition governments.
Coyne says the STV system will be simple for voters to understand. As he says, voters just need to be able to count to five. Yeah. Here in New Zealand, we have an even simpler form of PR: Mixed Member Proportional. Voters give one tick for a local candidate to be the local MP, the other for the Party they wish to get more seats in Parliament overall. The Party Vote determines the composition of Parliament, with first call on seats going to district-elected MPs. The system's been in place since 1996, but only about half of all voters understand which vote (Party or District) does more to determine the composition of Parliament. So here all they need to do is count to two, and they can't manage it. Counting to five would be right out.
PR is great for folks who like process for the sake of process. The composition of Parliament under PR reflects proportionate support for various parties. But it's a terrible way to form a government and hold it accountable. It yields bad policy outcomes. First Past the Post, on the other hand, is procedurally ugly. The composition of Parliament can be at large variance from aggregated national voter preferences. But at least it gives voters an easy way to throw out an underperforming government: vote for the other guy. Under PR, voters can't tell who to blame for policies they don't like and don't know for whom to vote to punish that party. My bottom line on evaluating electoral systems is to look at the results they've produced elsewhere (see Persson and Tabellini, above) and to think through how easy it is for the median voter to cast a ballot turfing out the incumbent. The latter is, to my mind, the most critical feature of a democratic system. If all else fails due to voter ignorance, we might hope that retrospective voting can form a simple rule to follow: support the incumbent if you're happy, and vote for the Opposition if not. It's tough to do even that under PR.